Novel Magnesium Protective Coatings Offering Excellent Corrosion Performance

Abstract

There has been a growing interest in using magnesium alloys in automotive, industrial, and aerospace applications due to their low density, high strength-to-weight ratio, good machinability, and low cost. These alloys have the potential to lighten cars and aircraft, reducing their fuel consumption and emissions. A major drawback to magnesium alloys is their highly reactive nature, which results in corrosion. Through a project administered by the U.S. Automotive Materials Partnership (USAMP), PPG focused on the development of metal pretreatment solutions for different magnesium alloys to address the reactivity challenge, while eliminating the use of chromium, a carcinogenic and environmentally toxic corrosion inhibitor used in existing magnesium pretreatment solutions. A major technical advance was accomplished by creating several chromium-free cleaning and pretreatment processes that offer excellent corrosion protection when compared to a typical automotive pretreatment to combat magnesium’s reactive nature. This work also concentrated on optimizing the pretreatment solutions by making them compatible with magnesium and other metals without the need for additional process steps, enabling the use of magnesium in more multi-metal applications and greatly expanding utilization opportunities.